Nanocrystalline TiO2 catalysts with different anatase/rutile ratios have been successfully prepared using a single-step solution combustion synthesis (SCS). The synthesized powders were characterized using XRD, Raman, XPS, FT-IR, SEM, TEM, BET and UV–vis DRS. The effects of urea-to-nitrate molar ratio on the phase structure, morphology and photocatalytic activity of the TiO2 powders were investigated. Results show that the urea contents play an important role in controlling the crystal structure of the samples. Specifically, well-dispersed anatase/rutile TiO2 nanocomposites (anatase 66.2%, rutile 33.8%) with excellent photocatalytic activity can be obtained when the molar ratio of urea-to-nitrate is 0.50. The synergistic effect between the anatase and rutile is responsible for the enhanced performance of this material. Moreover, a thermodynamic calculation was performed to interpret the phase transformation mechanism during the combustion process.

•The fabricated pebbles can be densified (81% T.D.) at a low sintering temperature (850 °C).•The pebbles’ size can be controlled during the fabrication process.•Average grain size of the Li2TiO3 pebbles is less than 1 μm (0.82 μm).•The molar ratio of Li to Ti of the pebbles sintered at 850 °C keeps the value of 1.97 after sintering.Lithium titanate (Li2TiO3) ceramic pebbles were successfully fabricated by using hydrothermal and improved dry-rolling method. In the present work, ultra-fine Li2TiO3 powder of high reactivity was prepared via hydrothermal reaction, using anatase titania and lithium hydroxide as raw materials. The as-synthesized Li2TiO3 powder exhibits an average crystalline size as small as 100 nm. Improved dry-rolling method was employed to fabricate Li2TiO3 pebbles. The green pebbles can be well-sintered (81% T.D.) at a temperature as low as 850 °C for 3 h. The pebbles have good sphericity (1.08) and narrow diameter distribution (1.0–1.2 mm) with a crush load of 35 N. Scanning electron microscope (SEM) observations of pebbles showed that the ceramic grain size was below 1 μm and atomic emission spectrometer fitted with inductively coupled plasma (ICP-AES) results confirmed that atomic ratio of Li to Ti in the fabricated pebbles was 1.97.

A single phase Li2TiO3 powder has been fabricated through a facile solution combustion process, using citric acid as the fuel and corresponding nitrates as oxidants. The effect of fuel-to-oxidizer ratio (0.5–1.5) on the combustion process, the phase and microstructure of the products was investigated. By using different combinations of citric acid fuel and metal nitrates, the combustion mode could be controlled. When the fuel-to-oxidizer ratio is 0.75, an eruption combustion mode is realized. Thermodynamic analysis of the combustion reaction shows that as the fuel-to-oxidizer ratio increases, the adiabatic flame temperature during combustion also increases, but the measured maximum temperature decreases. The crystallite size of Li2TiO3 powders was calculated to be 18–36 nm at different combustion modes. The as-prepared Li2TiO3 powders exhibit excellent sinterability and can be sintered to 90.7% of the theoretical density at 800 °C. The grain size of the Li2TiO3 ceramics is around 800 nm.

•We synthesized Li2TiO3 powder by microwave-induced solution combustion in one step.•The combustion reaction only happened by microwave heating.•Changing total metal ion concentration will influence combustion process.•The as-synthesized powder shows good sinterability.Nano-crystalline Li2TiO3 powder was prepared by a microwave-induced solution combustion synthesis (MSCS) route using urea as fuel. It is observed that combustion reaction, which did not occur by conventional heating, happened when microwave heating was induced. The as-synthesized Li2TiO3 powder exhibits a narrow size distribution. In MSCS, the total metal ion concentration (Cm) in the starting solution plays an important role. By changing Cm values in starting solution, SCS process including ignition time, combustion period and reaction rate can be controlled. The as-prepared powder could be sintered up to 92.6% of the theoretical density at 1223 K.

A series of nanocrystalline V-doped (0.0–3.0 at.%) TiO2 catalysts have been successfully prepared by the one-step solution combustion method using urea as a fuel. The obtained powders were characterized by XRD, SEM, Raman, XPS and UV-Vis DRS. The effects of V doping concentration on the phase structure and photocatalytic properties were investigated. XRD, Raman, and XPS show that V doping diffuses into TiO2 crystal lattice mainly in the form of V5+ and causes a phase transition from anatase to rutile. V doping can widen the light absorption range of TiO2, with the absorption threshold wavelength shifting from 425 to 625 nm. The photocatalytic activity of V-doped TiO2 powders were evaluated by the photocatalytic degradation of methyl orange (MO) under visible light irradiation. It is found that V doping enhances the photocatalytic activity under visible light irradiation and the optimal degradation rate of MO is about 95.8% with 1.0 at% V-doped TiO2.

A lepidocrocite-like potassium lithium titanate K0.80Ti1.733Li0.267O4 (KLTO) with layered structure was synthesized by an auto-igniting solution combustion method using glycine and metal (Ti, K and Li) nitrate as reactants. The crystalline structure and morphology of the as-prepared product were examined using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Effects of reaction parameters such as ignition temperature and oxidizers to fuel ratio on the phase formation and morphology evolution are investigated in this paper. A pure phase of KTLO was obtained at a low temperature (650 °C) within several minutes. Excessive glycine added into the aqueous precursor solution facilitated the synthesis of a pure and well-crystallized product. As-prepared particles exhibited plate-like shape with a length of 5–20 μm and a thickness of about 2 μm. No residual organic compound existed in the product. After the as-prepared product was post solution combustion heat-treated (1100 °C for 2 h), the particles became uniform in size with smooth surface and well-defined crystalline structure. The product exhibited excellent ion-exchange, intercalation, and exfoliation properties. The exfoliated titania nanosheets are characterized by high two-dimensional anisotropy with a thickness of about 20 nm and a lateral size ranging from sub-micrometers to several tens of micrometers.

Nanostructured Na0.5Bi0.5TiO3 particles have been synthesized by a hydrothermal synthesis method using a layered titanate H1.07Ti1.73O4·nH2O as a Ti precursor. The obtained Na0.5Bi0.5TiO3 particles showed different morphologies including plate-like, wire-like, and cubic-like structures in different hydrothermal conditions. The effect of the NaOH concentration on the growth and morphology evolution of hydrothermally derived Na0.5Bi0.5TiO3 powders were investigated. It was found that alkaline concentration had a great effect on the phase and morphology of the resultant powders. The dissolution–recrystallization and in situ topotactic transformation mechanisms were suggested in different alkaline concentrations according to the evolution process.

Bulk dense composites of Al–Fe alloys containing 2.5–10 at% Fe were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). Supersaturated Al(Fe) solid solutions were obtained by MA for 80 h. The sintered samples are composed of nano and ultrafine needle-like Al13Fe4 phase and angular-shaped Al13Fe4 phase with a size range of 1–2 μm uniformly distributed in the Al matrix. Needle-like Al13Fe4 phase originates from the precipitation of supersaturated Al(Fe) solid solutions, and angular-shaped Al13Fe4 phase originates from the reaction of undissolved Fe particles and the Al melt. The hardness of the alloys varied from 1.44 to 1.97 GPa and Al–10%Fe exhibited highest specific yield strength of 391.1 kN m/kg. The yield strength varied from 657 to 1130 MPa, depending on the Fe content. Excellent plastic strain (>14.5%) were achieved in the alloys containing 2.5–5%Fe, but the Al–10%Fe exhibited elastic behavior only, failing without any macroscopic yielding or plastic strain. The lack of plastic performance of Al–10%Fe is attributed to large amount of undissolved Fe particles reacted with the Al melt to form angular-shaped Al13Fe4, leading to the absence of soft α-Al phase.

A blue emitting phosphor of the triclinic BaCa2Si3O9:Eu2+ was prepared by the combustion-assisted synthesis method and an efficient blue emission ranging from the ultraviolet to visible was observed. The luminescence and crystallinity were investigated using luminescence spectrometry and X-ray diffractometry (XRD), respectively. The emission spectrum shows a single intensive band centered at 445 nm, which corresponds to the 4f65d1→4f7 transition of Eu2+. The excitation spectrum is a broad extending from 260 to 450 nm, which matches the emission of ultraviolet light-emitting diodes (UV-LEDs). The critical quenching concentration of Eu2+ in BaCa2Si3O9:Eu2+ phosphor is about 0.05 mol. The corresponding concentration quenching mechanism is verified to be a dipole–dipole interaction. The CIE of the optimized sample Ba0.95Ca2Si3O9:Eu0.052+ was (x, y)=(0.164, 0.111). The result indicates that BaCa2Si3O9:Eu2+ can be potentially useful as a UV radiation-converting phosphor for white light-emitting diodes (LEDs).